The link posted is for a one inch strip which is normally used in the area of your concern. If the opening of the channel as you see it is 5/8" then one inch is your size. If it is 1/2" you will need the 3/4 strip.
I'm pretty sure you are one inch but be sure to measure.
Don't stretch it when you put it on or you will wind up with the same problem.
Peace
Dave